The present invention generally relates to methods and apparatus for aligning rolls bearing strip material, e.g., in steel mills, paper mills, etc.
In industries where the rolling of thin strip material such as sheet metal, paper, film or fabric is encountered, a very important consideration is proper alignment of the roll system which transports the material. Improper roll alignment leads to the strip material moving laterally on the rolls, thereby wandering off the rolls completely or causing wrinkling of the material, which could cause material damage or stoppage of production.
Conventionally, when rolls need to be aligned, a plant may need to hire an outside survey team. The survey team is typically contracted to align the rolls through a complicated measurement and leveling process. The procedure is generally as follows:
1) Find the offset reference centerline. Level and align the transit to this offset reference centerline.
2) Rotate the transit exactly 90 degrees using the electronic indicator.
3) Place the center head on the top of the roll and verify that it is level.
4) Hook the steel tape on the top of the roll center head. Take a reading at each end of the roll.
5) Place the steel ruler against the side of the roll. Hold a level against the edge of the steel ruler to ensure that the ruler is level.
6) Slowly wave the ruler towards or away from the transit and take the minimum reading. This must be done on both ends of the roll that is being measured.
7) Compare the readings to determine the alignment of the rolls.
8) Place a machinist""s level, accurate up to 0.005 inches per foot, on the roll. Align the bubble to the middle of the level.
This process, however, can often be flawed, as there are many sources of error within the survey team""s system. For example, the measurements tend to begin with a tripod placed on the plant""s floor. This floor is assumed to be flat and level, which it may or may not actually be. Additionally, many measurements are taken relative to the previous measurements, allowing the error to propagate throughout the system. Clearly, there can also be a large amount of human error incurred in this process.
In the steel industry, the alignment tolerance for rolls must be kept very tight. In one industry standard, the rolls may not be misaligned by any more than 0.006 inches per foot of roll length. This means, for example, that a three-foot roll may be offset by no more than 0.018 inches in order to ensure a high-quality product. Currently, survey teams have been known to be inaccurate by as much as 0.250 inches per foot, which is over 40 times the tolerance just described.
Since the production line cannot operate during the roll alignment procedure, a rapid alignment method is also desirable. However, due to the complicated nature of the survey method just described, roll alignment can be very time consuming. Also, the usually high expense necessary to hire a survey crew is another major drawback to such conventional methods.
In view of the foregoing, a need has been recognized in connection with providing a system for aligning rolls that is quick, efficient and relatively inexpensive.
The present invention, in accordance with at least one presently preferred embodiment, broadly contemplates a rapid, inexpensive method for the alignment of rollers used in rolling operations and is intended to solve, inter alia, alignment problems in steel mills, paper mills, and in other venues involving the manufacture of a product that must be rolled or the handling and transport of strip material.
Generally, at least one presently preferred embodiment of the present invention broadly contemplates apparatus for aligning rolls, the apparatus comprising: a first structure for being associated with a first roll; a second structure for being associated with a second roll; a laser associated with one of the first and second structures; and a target associated with the other of the first and second structures; the first structure, the second structure, the laser and the target being adapted to indicate whether the first and second rolls exhibit an aligned condition with respect to one another.
Further, at least one presently preferred embodiment of the present invention broadly contemplates a method of aligning rolls, the method comprising: providing a first structure for being associated with a first roll; providing a second structure for being associated with a second roll; providing a laser associated with one of the first and second structures; providing a target associated with the other of the first and second structures; and employing the first structure, the second structure, the laser and the target to indicate whether the first and second rolls exhibit an aligned condition with respect to one another.
Finally, but not necessarily exclusively, at least one presently preferred embodiment of the present invention broadly contemplates a calibration unit for calibrating apparatus for aligning rolls, the calibration unit comprising: a first roll; a second roll; the first and second rolls exhibiting an aligned condition with respect to one another; a first structure associated with the first roll; a second structure associated with the second roll; a laser associated with one of the first and second structures; and a target associated with the other of the first and second structures; the first structure, the second structure, the laser and the target being adapted to indicate the aligned condition of the first and second rolls.